void TestHeuristic() {
  cout << "----------------------------------------------------------" << "\n";
  cout << "Heuristic Function Test: ";
  if (Heuristic(1, 2, 3, 4) != 4) {
    cout << "failed" << "\n";
    cout << "\n" << "Heuristic(1, 2, 3, 4) = " << Heuristic(1, 2, 3, 4) << "\n";
    cout << "Correct result: 4" << "\n";
    cout << "\n";
  } else if (Heuristic(2, -1, 4, -7) != 8) {
    cout << "TestHeuristic Failed" << "\n";
    cout << "\n" << "Heuristic(2, -1, 4, -7) = " << Heuristic(2, -1, 4, -7) << "\n";
    cout << "Correct result: 8" << "\n";
    cout << "\n";
  } else {
    cout << "passed" << "\n";
  }
  cout << "----------------------------------------------------------" << "\n";
}